In a stator of a rotary electric machine, a plurality of electric conductors of a winding wound around the stator are connected with each other using joining methods including welding in a coil end portion where the electric conductors project from an end of the stator in the axial direction. In the coil end portion of the stator winding where a plurality of connection ends are formed, it is necessary to secure electrical insulation between one connection end and another connection end, and electrical insulation between the connection ends and other components such as a casing of the rotary electric machine.
JP 2011-097779 A discloses an insulation cap for insulating connection ends of multi-phase windings of a stator of a rotary electric machine. The insulation cap includes a rear portion formed on a folded side of an insulation sheet which is folded into two leaves, and an opening portion which receives a connection end inserted thereto on a side opposite the rear portion. The opening portion is formed by joining both end portions of the folded sheets in the extending direction of the rear portion while leaving the side opposite the rear portion unjoined and open in the folded sheet.
JP 2003-111330 A discloses a method for insulating a plurality of joined portions collectively. With this method, a plurality of joined portions formed by joining tip ends of a plurality of conductor segments inserted into slots of a stator of a rotary electric machine are pressed onto a disc-shape cover member and plastically deformed thereby adhering to the cover member, and thereafter the joined portions are cured by heating.